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Old 10-13-2018, 06:27 AM
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Default Question for the lathe pros.

I got this 9 years old Enco 1440 lathe. I got it used and it came in with a 8" 3 jaw and a 10" 4 jaw chuck.
The lathe has a D1-4 3 stud mount. The previous owner never took off the 3 jaw so the 4 jaw
is brand new never been mounted. I had to put in the studs as they were still in the accessory box
packed in cosmoline. Taking off the 3 jaw went really hard. After mounting the 4 jaw I noticed that
it did not got pulled down to the flat part of the head stock so the chuck had some wobble. I cleaned
the surfaces well even using some scotch bright. No go. I went back to the 3 jaw and had the same
problem. I did not want to use excessive force but I can see some gap between the head stock and the
back of the chuck and it's wobbling about 5-10 thou. As I understand the D4-1 mount have a short taper
on the center but it has to sit down on the head stock as well. That last part is not happening on either
chuck. I checked the head stock and it has no run out at all. Should I try to lap the taper down so the
chucks sit down well? That's touchy as not to go too far. What do you guys think?
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Old 10-13-2018, 11:29 AM
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The three jaw was mounted so it should go back on. I hope you marked the relationship of the chuck to spindle before you removed it as they fit correctly only in that orientation.
Check carefully for burrs or chips. Tighten the mounts several times and it should bring the chuck into register. On the new chuck the studs need to be correctly adjusted so when the chuck is tight the key locating marks are in the correct zone between the indicators on the spindle.
If you must adjust the clearances do so on the chuck as it is the replaceable part.
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Old 10-13-2018, 11:57 AM
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The studs are adjustable in and out. I will take some pictures of mine.

Sounds to me like you don't have the studs adjusted properly.


Also +1 on what Terry said.
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Old 10-13-2018, 03:23 PM
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The studs are fine, within the range necessary. The problem is the taper. The
head stock seem a bit big so the chuck will not pull onto the flat part of the
headstock.
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Old 10-13-2018, 09:32 PM
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Something wrong somewhere. I have handled dozens and dozens of D series chuck mounts and I can't think of a single situation where, as long as the studs were at the correct depth, the chuck didn't seat properly. The fact that the smaller chuck was hard to remove is a sign in itself. With any that I have seen once the studs are loosened all it ever takes is a light tap with a soft hammer to release the chuck.

Take the studs out of both and see how everything fits up. Put some machinist's bluing on the spindle and check the fit of spindle to chuck. You may have some tiny burrs or raised spots that are the problem. If they won't seat properly after this I don't know what to say because I've never seen anything like it.

If you feel you must sand or otherwise clean up the surfaces do not under any circumstances touch the spindle with anything other than steel wool. It will remove rust or debris without removing any material. You don't have to remove much material to forever lose the accuracy of the lathe...
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Old 10-13-2018, 11:17 PM
threepiece threepiece is offline
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Quote:
Originally Posted by Bubba View Post
The
head stock seem a bit big so the chuck will not pull onto the flat part of the
headstock.
For the purpose of clarity, what you are calling "head stock" is actually called the spindle.

I have no idea why you have this issue. As a countermeasure perhaps you could make a set of shims from shim stock and place them between the chuck and spindle.
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Old 10-14-2018, 12:15 AM
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Quote:
Originally Posted by threepiece View Post
...As a countermeasure perhaps you could make a set of shims from shim stock and place them between the chuck and spindle...
If you do that chances are the tapers on the chuck and spindle won't fully centre--bound to cause some runout. As I said before there is a problem somewhere--if it isn't fixed properly the chucks will never mount correctly. Do the bluing thing and let us know what you find. Some pics would probably help too...
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Old 10-14-2018, 09:12 AM
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Walter,

I assume this lathe in in Wyoming? Pictures might help.

Ron
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  #9  
Old 10-14-2018, 10:35 AM
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Yes I'm now in Wyo. Here are some pics. I can assure all that there
are no burrs and crap around. I did everything with scotch bright.
The type has (brown) very little abrasive in it. As you see the spindle
has seen daylight just recently. All the studs in the right place and
the marks all around in the right range. I also marked with a small x
the chuck and spindle so everything is in the right order. I blued up
the spindle and see the results. Also when it's up I can fit in a 0.03mm
filler gauge in the gap.
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Old 10-14-2018, 02:32 PM
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Quote:
Originally Posted by Bubba View Post
...Also when it's up I can fit in a 0.03mm filler gauge in the gap...
Theoretically the back face of the chuck should just touch the face of the spindle when the chuck is properly seated but I don't think it has to. The taper is what actually locates the chuck, both on the centreline of the spindle and in a plane 90 degrees to the centreline. I don't think the gap by itself is a problem but I might be wrong. If you think about it this makes sense because if you have a situation where the two faces bottom out before the taper seats then the centreline of the chuck can be slightly off. If the taper seats first and is ground true then the chuck should be perfect.

After cleaning things up do you still have runout issues? And I suppose it would be difficult to find another chuck to check against your spindle? What did you see when you blued the assembly? Any chance of a pic?

As a point of interest the brown Scotchbrite is actually quite abrasive. We use it all the time and when the pads are fresh they can remove a lot of material. There are several finer grades, with gray--I think--being the finest.

I'm a bit surprised by all of this because the D series mounts are undoubtedly the easiest to work with and the most consistent when mounting on a spindle...
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